I agree with the bold statement. I think, for some people they channel their frustration too much on one player whose influence on the wide field of issues is therefor overstated to a degree.
I personally would consider to let him go anyway - but for more pragmatic reasons. There is the chance that if we fix the issues we have with control you are talking about, then he would stick out even more. We don't know whether that would be the case but the chances at least are there. Some on here admit he isn't perfect without actually acknowledging his weaknesses. Many don't really emphasize how rare it is these days to have a player that is at home in the 10 areas but is still as untidy on the ball. That combination is rare and while pressing gives less and less time and space on the ball, this weakness is really hurting him and it might very well be one of the reasons why his play feels rushed in many situations.
I would consider selling him because he is one of the players in our squad who would generate good amounts of funds. I think, he slowly gets into the same territory where Casemiro was when we bought him, his stock is high and while we won't challenge for anything in the next year probably next two years funds could help us to setup a team this summer that will compete at a point in time in 2 or 3 years.
I know it seems counter-intuitive and again, I am not advocating selling him at any price, but I think we have to act smart. He isn't going to get better and while he is probably Uniteds overall best player these days, that isn't really saying much (because for all his traits, there are many teams out there who don't have such a player and still are more productive than we are) and I think it is a pretty safe bet to state that at 29 he isn't part of a successful United future. Moving away from us he also might get the chance to add to his personal trophy cabinet, something even I think he deserves.
The sooner the club realizes the recruitment of the last years led to another dead end (to a degree) the better and the more proactive we could act from the summer onwards. You just saw the mess, ETH tried to marry evolution/modernization and providing short term success and while it the project floated decently in season 1, it likely is going to sink after season 2 because he can't deliver success while simultaneously not looking as if his ideas are going anywhere. And one reason is that his ideas aren't working out because the squad composition is such a mess.